The present invention relates to an arrangement for making it possible to achieve a parallell or redundant marine drive train for a propulsion unit. The drive train comprise a housing and an input shaft penetrating the same, which shaft at its one end comprise means to connect the same to a primary drive source, preferably using an Otto- or Diesel cycle. To said shaft a clutch unit is connected, with which the rotation of said input shaft may be connected, reversed or disconnected. Further said drive train comprise on the one hand a transversally to said input shaft arranged countershaft, which is driven by the input shaft via a gear, and secondly a secondary drive source, preferably of an electrical or hydraulical kind, which secondary drive via an intermediary clutch is arranged at a first end of said countershaft, so that dependant upon whether the primary drive source is driven or not, said secondary drive source is driven either to drive the countershaft by itself or in co-operation with the primary drive source.